If you listed what phone your using I would have a better answer but here is a good guess for you. Some Bluetooth capable phones only have the ability to send voice signals over Bluetooth and not data. If you have one of these phones check your instruction manuel and see what it says. Your phone...
Yes, in order to get new phone at a discounted rate you must sign a new 2 yr agreement for each phone you upgrade. At&t charges an $18.00 upgrade fee per line that you choose upgrade. This fee is usually tacked on to the next billing cycle and isn't required to be paid when you buy the phones...